I put up some pictures of a DIY Cool Shirt Cooler I made on IG and had a few people reach out, so I figured I'd write up a guide. This was a quick and dirty 2-3 hour project, so pardon the half-assness of it. You'll still need a proper Cool Shirt or whatever accessories you're going to use this for, this is mainly going to cover the cooler-side specifically.
Here is a spreadsheet of all of the parts I used for this:
FlatBlack's DIY Kewl Shirt Cooler
I wanted to try out a super cheap cooler, as I was going to be drilling into it and didn't want to waste a bunch of money if it didn't work out. I went to my local Academy and got a $29 Igloo cooler that worked out quite well - the handle(s) and wheels make it really easy to move around when it's full of ice water, and the dimensions are perfect for my application. The Paragon and Cool Shirt "official" coolers use an $80 13 Quart Engel cooler as the base of the kit, and I've put an Amazon link in the spreadsheet in case you want to go with one of those - there are many different colors available, and it comes with latches, so that might be a good alternative to the cheap 16 Quart Igloo. Dimensions of each cooler are listed in the spreadsheet and on the product links - use this to confirm it’ll fit for your application (for me, I used a 15” Kirkey to mount the cooler, and needed to stay within that width).
Once you've decided what cooler you want to use, you'll need to get some brass fittings, vinyl hose, caulk (all available at your local big box home store), a 12V submersible pump, and some electrical connectors for the pump (Available online via Amazon or similar). The only proprietary fittings/parts you need are the emergency-pull bulkhead fittings. I used Paragon fittings bought through Pegasus Racing, other brands/suppliers are available.
First, I marked out the limit of the ‘range’ of the top handle so it wouldn’t interfere with my bulkhead fittings. I offset my fittings with one closer to the top for hose routing reasons, but if you don’t have space restraints, you can put them anywhere. I believe the return needs to be near the top so the return water has less resistance, but the pump should be able to move water even if it’s lower. Next, I marked where I wanted the bulkhead fittings to mount on the cooler with a Sharpie.
For the exterior holes, you’ll want to drill the holes in the cooler very close to the size of the fitting threads to prevent leaks, but I used a Christmas Tree bit and was able to achieve a snug fit. The bulkhead fittings were tight enough to “thread” into the side of the cooler.
For the interior holes, you need to drill them out much wider than the exterior holes, as they need to fit the brass barb fittings for the tube, as well as allow for a wrench/socket to go over the fitting to tighten in. You’ll also want to make another hole for the pump wires to go through. I drilled a snug-fit hole for the pump wires just above the return fitting on the exterior, and ran the wires through the same interior hole for the internal brass fitting. You’ll need to clear out some of the foam insulation to make room as well.
Next, install the brass ⅜” barb to ⅜ NPT female fitting onto the bulkhead connector, and tighten everything up - you’ll want to clock the bulkhead fitting to an orientation to make it easy to click the tab to release the shirt hose, so make sure they are oriented properly. Next, cut 12-24” of vinyl tube and let it sit ‘loose’ in the cooler for the return hose. I made mine long enough to reach outside of the cooler in case I wanted to use the pump to empty the cooler. Next, put the submersible pump in the cooler, making sure it can rest “free” on the bottom of the cooler. Cut some vinyl tube to mate the pump to the lower pressure-side bulkhead fitting (the length of hose for the pump-side fitting will be determined by your cooler).
An aside about the pump: The ‘OEM’ Paragon/Cool Shirt pump is a nice German-made 12V Comet submersible pump, and I’ve included a link in the spreadsheet. I recommend using the Comet, but they seem to ship from Germany, and I’m impatient, so I bought a cheap $15 pump on Amazon. It worked great for the several sessions I used it, and has enough flow/pressure to run the cool shirt and helmet attachment. My shirt stopped working at COTA, and when I looked at the pump, the housing had popped off of the bottom. Run a zip tie lengthwise around the pump so that the bottom housing doesn’t accidentally become detached.
Run the pump wiring out of the cooler through the hole (leaving a little bit of slack for when the pump moves around), and then caulk up the holes near the fittings and wire. I let the caulk cure overnight before I tested the cooler out.
To power the pump with a 12V power source, I used 3.5mm x 1.35mm barrel plugs, as that is what matched the battery and pump wiring that came with my soft-sided Paragon cooler. I have links for both ends listed in the spreadsheet - they are very inexpensive and are very easy to connect/disconnect. In my racecar, I wired the power-side connector into a spare switch on my switch panel, and ran the wires to near the cooler mount in a convenient location.
While I normally have the pump powered by car power, I also have a soft-sided Cool Shirt cooler that I like to use as a mobile setup. The battery from Cool Shirt is VERY expensive for what it is (an 8V rechargeable battery), and you can use basically any 5-12V battery to use outside of the car. I cut up a USB Type A cord to connect to the 3.5mm barrel plug, and I ran my cool shirt at 5V off of a battery bank I had - most options should work, get creative.
To mount the cooler, I used a 15” 38-series Kirkey on a custom bracket I made.
https://kirkeyracing.com/products/kirkey-racing-38-series-aluminum-seat-aluminum-10-to-20-standard-layback-seat?variant=43119181791286
You can buy cool shirt cooler-specific mounting plates, but they are expensive for what they are, considering it’s a bent piece of flat metal. I’ve included some options in the spreadsheet if you want to use a pre-made mounting plate. The fittings were a little too close to the rib-protectors on the seat, so I used some high-density foam to raise the cooler up to provide better access to the bulkhead fittings. Out of an abundance of caution, I also added some riv-nuts to the seat and an aluminium bar to keep the cooler from sliding forward in case the harness belts were not enough. I also added two bungie cords to keep the lid down.
The cooler is now ready to test fire! Fill the cooler with water and ice, just below the fittings (it’s also fine to submerge them). I hooked the extension lines and shirt up to the cooler, and used the brass T-fitting drain to make sure it was functioning as expected. It takes a few seconds to start flowing - if it doesn’t move any water, make sure none of the vinyl lines are kinked. You should see a decent flow coming out of the return line. If it flows well, you are ready to hit the track.
On track, I used both my Cool Shirt and the Paragon Helmet attachment. Unfortunately, the helmet attachment worked TOO well, and it was pretty painful. I had to cycle the pump on and off every few minutes, otherwise I would have a brain freeze. Later in the day, I put it directly under my butt, and it worked really well as a seat cooler. I’ve heard that just some airflow into the helmet is really all you need.
I’ve been warned that the cooler really needs an o-ring to prevent the water from sloshing out, but the Igloo never let any water out through several sessions in my 240SX Time Attack car at COTA. I was running within a second or two of my PB pace, so it was getting a workout. To be safe, you could throw a towel under the cooler to soak up any water that spills. I have some bungie cords to keep the lid closed, but I will eventually add a latch to the cooler.
Overall, the benefit of this setup is incredible - the temps at the track during the summer months in Texas get pretty freakin hot, and I was experiencing heat exhaustion regularly last summer. It hasn't been hot-hot yet, but I've already seen how much this helps keep my brain functioning at 100%.
Stay cool out there!
